Analytical solution for soil flushing using PVD system with rectangular pattern

Abstract

Soil flushing using prefabricated vertical drains (PVDs) is an innovative subsurface remediation technology for contaminated fine-grained soils. An analytical solution is presented to investigate the performance of a PVD-enhanced system arranged in a rectangular pattern for soil remediation. The analytical solution is derived based on a simplified equivalent model in which PVDs are substituted by drain walls. The results of the analytical solution are shown to be roughly consistent with those obtained from the finite-element method. Using the proposed solution, the remediation efficiency for a rectangular layout is demonstrated to be higher than that for a parallel layout. Furthermore, the effects of distance between injection and extraction PVD, injection rate, distribution coefficient, and dispersivity are investigated. Results indicate that a square pattern is the optimal layout of PVDs compared to other rectangular patterns. Increasing the injection rate of individual PVDs is an effective way to improve the remediation efficiency. The increase of distribution coefficient of contaminant leads to a significant increase in the remediation time, and the increase of longitudinal and transverse dispersivity results in a more uniform spatial distribution of contaminant concentration during the flushing process.